Search Publications
Torque reversal and cyclotron absorption feature in HMXB 4U 1538-522
Jain, Chetana; Dutta, Anjan; Sharma, Prince
We present a comprehensive timing and spectral analysis of the HMXB 4U 1538-522 by using the Nuclear Spectroscopic Telescope Array (NuSTAR) observatory data. Using three archived observations made between 2019 and 2021, we have detected ~ 526 s coherent pulsations up to 60 keV. We have found an instantaneous spin-down rate of $\dot{P} = 6.6_{-6.0}…
Constraints on thermal conductivity in the merging cluster Abell 2146
Fabian, A. C.; Reynolds, C. S.; Hlavacek-Larrondo, J. +9 more
The cluster of galaxies Abell 2146 is undergoing a major merger and is an ideal cluster to study intracluster medium (ICM) physics, as it has a simple geometry with the merger axis in the plane of the sky, its distance allows us to resolve features across the relevant scales and its temperature lies within Chandra's sensitivity. Gas from the cool …
Galactic properties that favour star cluster formation: a statistical view
Sills, Alison; Eadie, Gwendolyn; Reina-Campos, Marta +1 more
The presence or absence of star clusters in galaxies, and the properties of star cluster populations compared to their host galaxy properties, are important observables for validating models of cluster formation, galaxy formation, and galaxy assembly. In this work, we apply a Bayesian approach to fit two models to data from surveys of young cluste…
Identifying and characterizing the most heavily dust-obscured galaxies at 1 ≤ z ≤ 4
Willott, Chris J.; Martis, Nicholas S.; Muzzin, Adam +2 more
We present 65 extremely dust-obscured galaxies from the UltraVISTA DR3 survey of the COSMOS field at 1 < z < 4. In contrast to other studies of dusty galaxies, we select our sample based on dust attenuation measured by UV-MIR spectral energy distribution (SED) modelling that allows for extreme attenuation levels. We construct our sample by m…
GMRT H I mapping of mid-infrared bright blue compact dwarf galaxies W1016+3754 and W2326+0608
Li, D.; Tsai, C. W.; Sengupta, C. +3 more
We present the results from deep 21 cm H I mapping of two nearby Blue Compact Dwarf Galaxies (BCDGs), W1016+3754 and W2326+0608, using the Giant Metrewave Radio Telescope (GMRT). These BCDGs are bright in mid-infrared data and undergoing active star formation. With the GMRT observations, we investigate the role of cold neutral gas as the fuel reso…
Strange quasar candidates with abnormal astrometric characteristics from Gaia EDR3 and SDSS (SQUAB-II): optical identifications
Zheng, Zhen-Ya; Liao, Shilong; Qi, Zhaoxiang +7 more
There are some strange quasars with multiple Gaia detections or observed with abnormal astrometric characteristics, such as with large proper motions or significant astrometric noises. Those strange quasars could be potential candidates of quasar-star pairs, dual quasars (DQs), or lensed quasars (LQs). Searching for both DQs and LQs is of great im…
Constraints on clumps in the representative wind of the WN8 Wolf-Rayet star HD 96548 = WR 40 with simultaneous broad-band light and linear-polarization variability
Ignace, R.; Moffat, A. F. J.; Robert, C. +1 more
We report precision ground-based broad-band optical intensity and linear-polarization light curves for the sky's brightest WN8 star, WR 40. WN8 stars are notorious for their high level of variability, stemming from stochastic clumps in their strong winds that are slower and less hot than the winds of most other Wolf-Rayet (WR) stars. We confirm pr…
Spectroscopy of TOI-1259B - an unpolluted white dwarf companion to an inflated warm Saturn
Triaud, Amaury H. M. J.; El-Badry, Kareem; Fitzmaurice, Evan +7 more
TOI-1259 consists of a transiting exoplanet orbiting a main-sequence star, with a bound outer white dwarf (WDs) companion. Less than a dozen systems with this architecture are known. We conduct follow-up spectroscopy on the WD TOI-1259B using the Large Binocular Telescope to better characterize it. We observe only strong hydrogen lines, making TOI…
The orbits of outer planetary satellites using the Gaia data
Emelyanov, N. V.; Kovalev, M. Yu; Varfolomeev, M. I.
Launch of the Gaia space observatory started a new era in astrometry when the accuracy of star coordinates increased by thousands of times. Significant improvement in accuracy was also expected for the coordinates of the Solar system bodies. Gaia Data Release 3 (DR3) provided us with the data that could be used to test our expectations. In this wo…
VLT-MUSE spectroscopy of AGNs misclassified by BPT diagnostic or with weak emission lines
Janowiecki, Steven; Boquien, Médéric; Salim, Samir +3 more
Despite powerful X-ray emission, some active galactic nuclei (AGNs) are known to either lack optical emission lines (so-called 'optically dull' AGNs) or have lines that fall on the star-forming branch of the Baldwin-Phillips-Terlevich (BPT) diagram ('misclassified' AGNs). Aperture effects have been proposed to explain such atypical spectra, especi…